Abstract

The investigation is focused on the phenomenon of heat transfer deterioration (HTD), inhibiting the use of supercritical fluids in the processes in which high-power local heat release is possible. The ordinary discussion is based solely on the data of quasi-stationary measurements. In order to clarify the intrinsic nature of HTD as an essentially non-stationary phenomenon, it is worthwhile to take into account the peculiarities of heat transfer confined in time and space. In the present paper, we briefly discuss the characteristic features of such heat transfer in supercritical water. The characteristic heating time was \(10^{-3}\div 10^{-2}\) s and the heat flux density through the wall increased up to 15 MW/m\(^{2}\). The results provide the heat transfer pattern under conditions of predominance of the heat conduction mode. Exactly this mode most closely corresponds to the regime of high-power local heat release in a viscous sublayer. We also propose that the effect of threshold decrease in the heat transfer intensity (typical of pulse processes in supercritical transitions) may be a fundamental factor for occurrence of the HTD mode.

中文翻译：

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标题超临界水中的大功率放热：深入研究传热恶化问题

摘要

研究集中在传热恶化（HTD）现象上，该现象会抑制可能在大功率局部释放热量的过程中使用超临界流体。普通讨论仅基于准静态测量的数据。为了阐明HTD本质上是一种非平稳现象的内在本质，有必要考虑时间和空间内传热的特殊性。在本文中，我们简要讨论了这种在超临界水中传热的特征。特征加热时间为\（10 ^ {-3} \ div 10 ^ {-2} \）  s，通过壁的热通量密度增加至15 MW / m \（^ {2} \）。结果提供了在热传导模式占优势的条件下的传热模式。确切地说，这种模式最接近于粘性子层中的高功率局部放热状态。我们还提出，传热强度阈值降低的影响（超临界转变中脉冲过程的典型情况）可能是发生HTD模式的基本因素。